1. Field of the Invention
The present invention relates to a light exposure mask and a method of manufacturing the same, and more particularly, to a light exposure mask and a method of manufacturing the same for use in a liquid crystal display (LCD) device.
2. Description of Related Art
FIG. 1 is a plan view illustrating a typical LCD device. As shown in FIG. 1, the typical LCD device comprises gate lines 60 arranged in a transverse direction, data lines 70 arranged in a longitudinal direction perpendicular to the gate lines 60, thin film transistors (TFTs) xe2x80x9cSxe2x80x9d located near cross points of the gate lines 60 and the data lines 70, and pixel regions 40 defined by the gate lines 60 and the data lines 70.
The typical LCD device is manufactured by the following processes. FIG. 2 is a cross-sectional view taken along line ∥xe2x80x94∥ of FIG. 1. First, a gate electrode 60a is formed on a transparent substrate 10, and then a gate insulating layer 50 made of a inorganic material such as SiNx or SiOx is formed on the whole surface of the transparent substrate 10 while covering the gate electrode 60a. The gate electrode 60a contacts the gate line 60. Sequentially, a semiconductor layer 80 is formed over the gate electrode 60a in the form of an island. The semiconductor layer 80 has an amorphous silicon layer 80a and a doped amorphous silicon layer 80b. Source and drain electrodes 70a and 70b spaced apart from each other are formed overlapping a region of both ends of the doped amorphous silicon layer 80b. The source electrode 70a contacts the data line 70, and the drain electrode 70b contacts a pixel electrode that is formed in a subsequent process. Then, a passivation layer 55 is formed on the whole surface of the transparent substrate 10 covering the source and drain electrodes 70a and 70b, and then a contact hole 42 is formed at a predetermined location over the drain electrode 70b. The pixel electrode 44 is formed on the pixel region 40 to contact the drain electrode 70b through the contact hole 42.
Most components of the typical LCD device described above are formed using several photolithography processes. In the conventional photolithography process, as shown in FIG. 3A, a metal layer 90 is formed on the substrate 10. Either a positive or a negative photoresist is applied on the metal layer 90, and then a light exposure mask 88 is aligned. FIG. 3A shows the positive photoresist 100, and the light exposure mask 88 has light transmitting regions 88a, 88c and a light shielding region 88b. Sequentially, when UV light is irradiated toward the light exposure mask 88, the photoresist 100 is developed, thereby forming a photoresist pattern 10a shown in FIG. 3B.
Then, the photoresist pattern 10a is subjected to a predetermined temperature and atmosphere to become hardened. The metal layer 90 is etched according to the photoresist pattern 100a using either of a dry etching technique or a wet etching technique so that a metal pattern layer 90a is formed as shown in FIG. 3C. Finally, the photoresist patter 100a remaining on the metal pattern layer 90a is removed.
However, when using the conventional light exposure mask 88 described above, since the light transmitting regions 88a, 88c and the light shielding region 88b of the light exposure mask 88 transmits and shields the UV light perfectly, respectively, the metal pattern layer 90a formed comes to have an almost rectangular-shaped cross section. Therefore, when another metal layer (not shown) is formed on the rectangular-shaped metal pattern layer 90a, there arises a problem in that step coverage becomes degraded so that an open line may occur at a step portion.
FIGS. 4A through 4C show another photolithography process to form a dual-layered metal pattern layer. As shown in FIG. 4A, first and second metal layers 90 and 91 are sequentially formed on a transparent substrate 10, and a positive photoresist 100 is applied on the second metal layer 91. Then, a light exposure mask 88 having a light transmitting region 80a and a light shielding region 80b is aligned. Sequentially, when UV light is irradiated toward the light exposure mask 88, the photoresist 100 is developed, thereby forming a photoresist pattern 100a as shown in FIG. 4B.
Then, the photoresist pattern 100a is subjected to a predetermined temperature and atmosphere to become hardened. The first and second metal layers 90 and 91 are simultaneously etched according to the photoresist pattern 100a using either of a dry etching technique or a wet etching technique so that first and second metal pattern layers 90a and 91a are formed, as shown in FIG. 4C. Finally, the photoresist pattern 100a remaining on the second metal pattern layer 91a is removed.
However, when using the conventional light exposure mask 88 described above, the metal pattern layers 90 and 91 inevitably have the same shape, thus, in order to form different shaped metal layers, an additional photolithography process should be performed again, leading to a lengthy processing time and a low yield.
To overcome the problems described above, preferred embodiments of the present invention provide a light exposure mask having a substrate defined by the following three regions: a light transmitting region, a light shielding region and a light semi-transmitting region.
Another embodiment of the invention provides a method for manufacturing a light exposure mask having a light transmitting region, a light shielding region, and a semi-transmitting region, comprising the steps of: preparing a transparent substrate; forming a semi-transmitting layer and a light shielding layer on the substrate in this order; patterning the light shielding layer to define the light shielding region of the substrate; and patterning the semi-transmitting layer so that the semi-transmitting region of the substrate is covered by the patterned semi-transmitting layer.
The light shielding layer preferably has Cr/CrOx, and the semi-transmitting layer preferably has indium tin oxide.
Another embodiment of the invention provides a method for manufacturing a light exposure mask having a light transmitting region, a light shielding region, and a semi-transmitting region, comprising the steps of: preparing a transparent substrate; forming a light shielding layer on the substrate; patterning the light shielding layer to define the light shielding region of the substrate; forming a semi-transmitting layer on the substrate while covering the patterned light shielding layer; and patterning the semi-transmitting layer so that the semi-transmitting region of the substrate is covered by the patterned semi-transmitting layer.